Protecting device for electric detonators



Aug. 24 1926. 1,597,446

H. L. GRANT PROTECTING DEVICE FOR ELECTRIC DETONATORS Filed Nov. 20, 1925 vwcntoz flarry Z. Grant,

' Serial No.

Patented Aug. 24, 1923.. v

UNITEDYSTATES PATENT OFFICE- HARRY L. GRANT, OF TAMAQUA, PENNSYLVANIA, ASSIGNOR TO ATLA S POWDER COM- IPANY, OF WILMINGTON, DELAWARE, A CORPORATION OF DELAWARE.

PROTECTING DEVICE FOR ELECTRIC DETONATORS.

Application filed November 20, 1925. sri rm. 70,371. X

This invention relates to a protecting de-' Vice for electric detonators of the character of that shown in my copending application, 748,214, filed on November 6, 1924.. K

Like the device of the application referred to, the protecting device'of the pres ent invention is intended to be applied to v the lead-in wires of electric detonators and to serve, while in position, to establish a short circuit between the two lead-in wires,

so that any stray currents imposed upon the lead-in wires, outwardly of the point of application of said device, may not findtheir way to the detonator and prematurely explode the same. i p

I am aware of the fact that it has been proposed to short circuit the main firing cable leading from the blasting machine. However, that method is of .utility only at the time of use. An important object of the present invention is to provide a structure which will be operative with respect to the individual detonators and their indi-:

vidual lead wires, at all times between the time of manufacture of the detonator and until the same is actually exploded on the job, the structure being of particular utility during the time that the detonator is being transported and while it is being handled about the work preliminary to. the actual connection of its lead wires to the main firing cable. By individual lead wires I mean the lead wires forming part of and shipped with the individual detonators and by which. said detonators are connected to the main firing cable.

The present application is directed to the protection of a specific form of short circuiting'shunt and method of applying the same to the lead-in wires of the individual blasting caps, at a point close enough to the Fig. 1 is .a perspective view of a clip or shunt constructed in accordance with the invention. v

Fig. 2 is a side elevation of the detonator .withthe clip of Fig. 1 applied thereto, and

Fig. 3 is an end elevation of the shunt with the bared portions of the lead wires of the detonator-in section.

Like numerals designate corresponding parts in all of the figures of the drawing.

Referring to the drawing, 5 designates the conventional electric detonator and 6 and 7 designate theusual'lead-in wires of said detonator.

In the'ordinary use of the detonator the fiow of current of' sulficient strength past an igniting element 8, which connects the inner ends of the wires 6 and 7, explodes the detonator. The lead-in. wires are insulated, as indicated at 9 and 10, for some of the lead wires are held by the resilient action of the structure, -which is' preferably, though not necessarily, made "of phosphor bronze. However, it is to be understood that it may be made of any suitable conductive and resilient material.

By referring to Fig. 1, it will be seen that the shunt consists of a piece of metal bent upon itself. to constitute the plate-like portions 11 and 12. The or'tion 12' is provided with an outturned edge 13 to facilitate the entry of the lead wires, 6 and 7, between the webs or plates 11 and 12. The mner face of the plate 12 is grooved, as indicated at 14, to provide a recess which extends throughout the length of the shunt and into which the wires 6 and 7 snap, and in which they are firmly held in engagement with each other, it being understood that the shunt, as a whole, is preferably positioned upon these lead wires with its inner end abutting snugly against the outer ends of the insulation of said lead wires. It is not to be understood that the device is of utility only when actually touching the termination of the insulation. It will give a very appreciable measure of protection even when spaced somewhat from the insulation because the influences which might bring about such difference in potential between \the lead wires as to explode the detonator, are not those sought to be created by an intelligent human agency but only those which might accidentally occur. Stray currents of such low E. M. F. as to escape ordinary notice constitute a marked source of danger and are rendered absolutely harmless by this invention.

When the shunt is to be removed, at the time of use of the detonator, it may be slipped laterally from the wires or it may be stripped longitudinally therefrom. If stripped longitudinally from the wires, such stripping action tends to clean and brighten the Wires and put them in condition to form an eflicient electrical union with the main firing cable of the blasting machine.

It is to be understood that the invention is not limited to the precise construction set forth but that it includes within its purview whatever changes fairly come within either the terins or the spirit of the. appended claims. I

Having described my invention, what I claim is:

1.. A shunt of the character described formed of an integral piece of sheet metal,

bent upon itself, one "of the bent/ portions being longitudinally ribbed and grooved at a point spaced from the point of bending,

with the grooved portion disposed inwardly,

said grooved portion being of such amplitude as to receive both of'the lead wires of a detonator and hold them into contact making engagement throughout the length of 'piece of sheet metal, bent upon itself, one of the bent portions being longitudinally ribbed and grooved with the grooved portion disposed inwardly, said grooved portion receivin both of the lead wires of the detonator and holding them in contact making engagement, at a point between the termination of the insulation and the outer ends of the said lead wires.

In testimony whereof he afiixes his signature.

HARRY L. GIRANT. 

